Amp Tech Thread / Ask a tech Q

[mortlock]

yes..that is correct..non responsive except a loud hum when amp is turned on..

[Hemisaurus]

Well if none of the tone controls affect it, and none of the inputs produce any sound, then your problem is in the power amp section. The fact that there's a loud hum, means the power transistors are still alive, or at least one of them is, if you had an O/C or S/C the cone would pop when you turned it on, and then no further noise.

Are you planning to try and fix it yourself? It's the sort of job that would be really easy with an oscilloscope, you'd just backtrack from the output and see where the hum stopped. Without one, I guess you could try and probe it and listen for clicks. It's only 43V so it won't kill you, like a tube amp might, as long as you stay away from the power transformers connection to the mains.

That's me assuming of course it's a Bandit 65, and reading from that schematic, maybe it's not, maybe it's some other model which has a higher DC supply voltage.

[mortlock]

fixing it myself is out of the question. way out of my league..is it even worth fixing..i only paid a hundred bucks for the amp to begin with..

[Hemisaurus]

Err, so what was the technical question

[mortlock]

the question is what the heck did i do to my amp..??

what is the lowest power rating amp i can get away with using for the 2 to 3 syths i pump through it..i cant afford to keep blowing amps up.
the bandit was an 80 watt amp..and i fried it right out of the gate..

[Hemisaurus]

I think there's sort of a misconception here. The power rating of the amp does not dictate what input it can handle. You may have forced the amp to blow up by driving it too hard, but you can connect the synths to any amp, just don't turn everything up to 11.

For the frequency range of a synth, lots of low frequencies and square waves, a bass amp might be the way to go.

[mortlock]

i told you i was a fucking moron when it comes to this shit.

[Hemisaurus]

I guess with synths it makes it difficult to spot the nasty buzzy farty sounds of your amp reaching destruction, from the nasty buzzy farty sounds of your synth

So bass amp, don't go beyond 7, 'til you're sure it's safe

[mortlock]

thats what i needed..thanks.

[bitter]

Question: My verellen has kind of a weak clean channel. It stays clean but doesn't have a great deal of volume on tap. When I want to use pedals, I find that I have to crank the effect's output, use most of the preamp volume, and then bump the master up to ~2 o'clock. If I have too much bass or output (say from a clean boost after a fuzz) the amp gets glitchy and then massive volume drop??? Usually dropping the volume and toggling from clean to crunch fixes it. Still, it's always done this and it's making me want to get something else or swap preamp tubes to clean up the crunch channel and use it for pedals.

[Hemisaurus]

I've never worked on a Verellen, but I wouldn't imagine it's meant to be that way. I'd contact Verellen, or failng that, your local qualified amp tech. Even if it is functioning as designed, handwired amps are easy to modify. You say it's always done this, have you ever had the preamp tubes changed?

[bitter]

Yeah, back in '09. I had a bad preamp tube that was causing all kinds of popping and arcing.

It only seems to happen on the rare occasions when I drive the amp hard, but not harder than would be expected of a 100 watt amp.

[Hemisaurus]

I'd suspect a bad pre tube again. You could try swapping around the pre tubes, or just replacing them.

[VOLVO)))]

You can send it to me at:

Mumumbo Tinigard
1384 Kalishnikov Way
Clickclick, Nigeria 656-655

I will deposit three thousand monies into your bank account upon arrival

Sent from my DROID X2 using Tapatalk

[bitter]

Alright, I'll look into that. Prolly just swap the whole set because Ben mentioned something about a bad batch of preamp tubes when he looked at it in '09. I think he just swapped the single offender that time.

[liquidsmoke]

I put my new 16 ohm speakers in my 2x12 and took it in to have it wired properly because I didn't want to fuck it up(okay I'm a loser, even though I'm planning on tearing half my motorcycle apart and putting it back together and riding it 70-80+ mph). I told them to wire it parallel for 8 ohms. I get it home and this is what I see-

a black and a white wire from the jack to speaker 1

a black and a white wire from speaker 1 to speaker 2

That's it. Is this correct? I don't want to burn up my amp.

I thought there was supposed to be a wire connecting the + wire that goes from the jack to speaker 1 to the positive terminal on speaker 2, or something funky like that as this overly simplistic diagram shows-
http://www.eminence.com/support/wiring-diagrams/

The thing is that each speaker has 4 metal tabs for wires to attach. This is why I didn't try this myself, it just confused the shit out of me.

Grrr...

[Hemisaurus]

So two wires from the jack to speaker 1, and two wires from speaker 1 to speaker 2, sounds right.

For parallel you connect jack > + on Speaker 1 > + on Speaker 2
                      sleeve of jack > - on Speaker 1 > - on Speaker 2

so sounds right.

The 4 tabs are just so you can parallel up connections, there's only a plus and a minus and the tabs are in an L on each



You can see the positive terminals marked on the left here.
                                                                         

[liquidsmoke]

So why do these diagrams I see online show a wire going from the wire before speaker 1 connecting to speaker 2?

[liquidsmoke]

[Hemisaurus]

It doesn't matter where you connect it, you could join the wires together, but it's easier in a lot of cases just connecting the wires together on one of the speakers using the 4 tabs, the two tabs either side are connected together it's like a jumper cable, you follow?

[liquidsmoke]

Excellent! Got cha. I'm going to crank the shit out of these fuckers right now.

[liquidsmoke]

And thanks!

[liquidsmoke]

To my ears the Swamp Thangs sound almost exactly the same as the Governors only they don't break up like crazy at high volumes. A O K.

[Instant Dan]

This is fifties guitar wiring? Correct?



P.S. I did not pay for those Gibson bumblebee cap fakes but feel sorry for whatever guy did.

[Jake]

Forgive me if this has been discussed in this (or other) threads before, but I'm wondering if you pros could help me with what might be a fairly simple DIY project.

I was considering making footswitchable volume knob pedal between my guitar and amp. I want to do this because there's a very small sweet spot when I back off of my guitar's volume knob into my overdriven amps, and it's really hard to roll back to it on the fly when I want to clean up the signal.

Would it be as simple as wiring a potentiometer and a switch to a pair of 1/4" jacks in a housing? Please say yes.

Something like this, but $40 or so cheaper: http://www.ebay.com/itm/The-Leech-Passive-Volume-Attenuator-Guitar-Pedal-with-LED-/330720454606?pt=UK_Guitar_Accessories&hash=item4d0079a7ce#ht_1019wt_1224